This study is designed to monitor the safety of Boostagen® after it has been approved for use in Thailand. The study follows people who receive the vaccine in routine medical practice to identify and record any side effects.

Doctors, nurses, and other healthcare professionals from hospitals and clinics in central, eastern, southern, and northern Thailand take part in the study. They report any health problems that occur after vaccination using standard reporting forms.

The information collected helps researchers understand how safe the vaccine is when used in a large and diverse population under real-world conditions.

Primary objective: To describe the post-licensure safety profile of Boostagen® in Thailand.

Secondary objective: To identify any unexpected safety signals following vaccination with Boostagen®.

HCPs eligible to participate were those who prescribed or administered Boostagen®. as a booster immunization in line with national guidelines. Recruitment was carried out in hospitals and clinics located in central, eastern, southern and northern Thailand. HCPs who agreed to participate were interviewed periodically regarding adverse events following immunization (AEFIs) with Boostagen®.

Data collection was performed using a standardized questionnaire administered monthly, either in person or by telephone. The questionnaire captured the number and type of AEFIs observed, along with other safety-related information.

HCPs used a modified WHO AEFI report form to document adverse events. In addition, a pregnancy safety outcome report form was developed to collect data on pregnancy outcomes among vaccinated pregnant women and their newborn. This structured approach enabled systematic monitoring's safety profile in real-world conditions and ensured early identification of any unexpected safety signals.

Statistical Analysis. No formal prespecified study hypothesis was established. Descriptive statistical methods were applied to summarize demographic and baseline characteristics of Boostagen® recipients, including children, adolescents, adults, and pregnant women. The incidence rates and proportions of AEFIs were calculated. For pregnant women vaccinated with Boostagen®, pregnancy outcomes, pregnancy-related complications, and neonatal outcomes were summarized. Continuous variables were described using means and standard deviations, while categorical variables were presented as frequencies and percentages. Ninety-five percent confidence intervals (95% CIs) were calculated where appropriate. All statistical analyses were performed using SPSS software, version 18.0 (SPSS Inc., Chicago, IL, USA).

Inclusion Criteria: An HCP will be eligible for inclusion if ALL of the following criteria are met at the time of screening:

1. Has prescribed and/or administered Boostagen® to children, adolescents and adults in accordance with current national immunization guidelines.
2. Employed full-or part-time (> 8 hours/week) in a government or private hospital or medical clinic.
3. Available for follow-up by telephone call, email or site visit if there are missing information in the study questionnaire, to confirm the occurrence or clarify the nature of an adverse event following immunization with Boostagen®.
4. Willing and able to comply with the study procedures.

Exclusion Criteria:

• Unwilling to take part in the study.

The study population consists of a cohort of HCPs working in private and government hospitals and clinics in central, eastern, northern and southern Thailand where Boostagen® vaccine is marketed. An HCP is defined as medically qualified person, such as physician, nurse or pharmacist.